The present invention relates to an adjustment device for an item of furniture and comprises two relatively mutually movable parts of which the one is elongate, cylindrical and longitudinally displaceable in relation to the other. The present invention also relates to the use of an adjustment device in an item of furniture such as a chair or a table.
Swedish Printed Application No. 458 332 describes an adjustment device which is intended for adjusting a chair so that its seat and back can be steplessly adjusted in relation to one another. The adjustment device includes an outer sleeve with slide bushings disposed at each end extending through a rod or a tube. Between the slide bushings, there is a clamping jaw or a sleeve which is urgable under the action of a screw against the rod for locking the rod in optional displacement position in relation to the outer sleeve. The construction according to this Swedish Printed Application functions satisfactorily, but is expensive to manufacture and difficult to remote control.
European Patent Application EP 0 A11 338 A1 discloses a similar adjustment device as described above wherein a helical spring is employed as a clamping device between the two relatively movable parts. While the device with the helical spring works well, there is a wear problem between the spring and the movable parts.
Accordingly, it is the principle object of the present invention to provide an adjustment device wherein the drawbacks inherent in the prior art devices described above are overcome.
It is a further object of the present invention to provide an adjustment device which is simple and economical to manufacture and easy to operate.
It is a still further object of the present invention to provide an adjustment device which affords reliable and dependable locking in any selected adjustment position and which possesses good mechanical strength and durability.